SURFACE – Coldstones Quarry is situated on Greenhow Hill at 1400 ft above sea level and is one of the highest quarries in Britain, the quarry currently covers an area of about 30 hectares. It is worked on 6 benches 15-18m high to a depth of 300m at the base. Coldstones provides an average of 600,000 tons of aggregate annually. Over 90% of its products are used locally within a radius of 30 miles. The limestone is crushed on site using a jaw crusher and produces aggregate from about 25ml down to dust, all of which is stored on the quarry top. The asphalt plant produces 50,000 tons annually. Any excess produced is stored and recycled as necessary. At the moment the plant is situated close to the quarry entrance, they are however going to be re-sited on the opposite side of the quarry. Greenhow Hill is an old mining area and there has been evidence of this over the years as old workings have been exposed. There are 2 mineral veins exposed within the quarry, the Garnet and Sun Vein.
One interesting geological feature is a sinkhole which has a sandstone and shale infill. The quarry has an estimated life of 10-15 years and after that time it is anticipated that it will be allowed to return to nature. On the way back to the car park we visited the Toft Gate Lime Kiln which is a large, fairly intact, kiln. The flue stack which is visible from the car park is attached to the kiln by a long well preserved stone flue.
The full meet report and photographs can be found in the August 2019 newsletter.